For example, in a manufacturing process of a semiconductor device, various processes such as an ion implanting process, an etching process, and a film forming process are performed on a substrate. In a batch-type processing apparatus such as an ion implanting apparatus that processes a plurality of substrates in a processing chamber, it is desirable to perform the unloading of a processed substrate from the processing chamber and the loading of a unprocessed substrate into the processing chamber at the same time, thus allowing the replacement of the processed substrate with the unprocessed substrate to be carried out in a short period of time. It is because the processing apparatus enters a standby mode and stops operation when the replacement of the processed substrate and the unprocessed substrate is performed, thus causing deterioration of a throughput of the processing apparatus.
In this regard, as disclosed in, for example, Patent Document 1, there has been conventionally proposed a substrate transfer apparatus in which substrate accommodation unit for storing therein substrates in multi-stages and transfer arms for transferring a substrate between the substrate accommodation unit and the processing chamber are independently installed for loading and unloading of the substrates into and out of the processing chamber.
In using the substrate transfer apparatus disclosed in, for example, Patent Document 1, the substrate processing apparatus still enters the standby mode, for example, when unprocessed substrates in another substrate accommodation vessel installed outside the system are transferred into the substrate accommodation unit by another transfer arm after all the substrates in the substrate accommodation unit are loaded into the processing chamber. In this regard, Patent Document 2, for example, discloses a transfer arm having a plurality of substrate holders in multi-stages as a means for transferring of the substrates between a multi-stage substrate accommodation unit and another transfer arm.    Patent Document 1: Japanese Patent Laid-open Publication No. H5-67668    Patent Document 2: Japanese Patent Laid-open Publication No. 2007-123592